Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/483—Physical analysis of biological material
  • G01N33/487—Physical analysis of biological material of liquid biological material
  • G01N33/49—Blood
  • G01N33/491—Blood by separating the blood components
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/10—Composition for standardization, calibration, simulation, stabilization, preparation or preservation; processes of use in preparation for chemical testing
  • Y10T436/107497—Preparation composition [e.g., lysing or precipitation, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T436/00—Chemistry: analytical and immunological testing
  • Y10T436/10—Composition for standardization, calibration, simulation, stabilization, preparation or preservation; processes of use in preparation for chemical testing
  • Y10T436/108331—Preservative, buffer, anticoagulant or diluent

Definitions

• the present invention relates to a serum separation sealant. More specifically, it relates to a serum separation sealant having an excellent balance of flow and specific gravity characteristics and an excellent storage stability.
• the present invention emplores the use of a thixotropic gelatinous material, dispensed in a test tube, in which blood (or blood plasma) is collected. Under the influence of a centrifugal force, the gelatinous material moves to a region between the upper serum (or plasma) and the lower solid blood clot portion due to the differences in the specific gravities, forming a partitioning barrier. The serum is then collected for clinical analysis. The formation of an effective barrier which separates the constituents and prevents the diffusion of blood cells back into the serum (or plasma) portion is the major function of a serum separator.
• Such a material must flow only under the influence of centrifugal force and maintain its dispensed position between the serum layer and the clot layer when the centrifugal force is relieved.
• the separator material it is desirable for the separator material to maintain its position, whereby the blood cell portion does not flow and the partitioning barrier is not broken with the lapse of days. This is especially important during transport or storage where the tubes may be subjected to such positions. Excessive flowability would render the tubes useless.
• the most suitable material for such a purpose possesses structural viscous properties, which is called thixotropic fluid properties, which impart a solid like behaviour during transient periods, and can break down during centrifugation, losing its solid properties, allowing for flow to occur.
• thixotropic fluid properties which impart a solid like behaviour during transient periods, and can break down during centrifugation, losing its solid properties, allowing for flow to occur.
• the gelatinous material has the ability to rebuild its network structure and retain its previous solid properties.
• Serum separators using such a principle were first suggested by U.S. Pat. No. 3,780,935 (Lukacs et al.) and U.S. Pat. No. 4,071,316 (Wright et al.), and consist of a network forming silica powder dispersed in a diorganosiloxane resin.
• 4,770,779 also entail using the same type of polysiloxane polymer, as a thixotropic agent, in a composite mixture of ⁇ -olefin-dimaleate copolymer and bentonite powder or silica. Another effect of using this thixotropic agent is the reduction in the concentration of network forming agents such as Aerosil and Bentonite powder.
• JP-B-1-1-25026 discloses gelatinous materials.
• a material with a structural viscosity such that it will not flow in the distribution stage.
• a centrifugal force for example, less than 1500G
• a short time for example, less than 10 minutes
• the viscosity of the gelatinous materials be low.
• the barrier of the gelatinous material, formed under centrifugation must be sturdy or firm to prevent breakdown during the decantation of the serum. Thus, it is necessary that the gelatinous material possess transport stability and partitioning ability and also exhibits excellent movability.
• U.S. Pat. No. 4,189,382 suggests the insertion of a cylindrical like object, referred to as an "Energizer", inside the gel tube, after dispensing. Its main function is to apply extra force on the gel body, at the onset of centrifugation, and initiate movement. It can also serve as a carrier for clotting agents. Similar proposals have been made, using glass beads.
• U.S. Pat. No. 4,770,779 suggests a specialized gel dispensing method such that a cone like cavity is formed on the upper surface. Such a condition, by virtue of the centrifugal force, also promotes the gel to readily flow. While these procedures are effective at maintaining reliability (or barrier formation), they require extra steps during dispensing, and add to the overall cost of the gel tube.
• gelatinous materials should exhibit little or no free flow properties, during transitory periods, regardless of the gel-containing tube position. It should maintain the initial dispensed position thereof, before actual use. If the gel exhibits excessive free flow, it could coat the entire tube surface, leading to remnant red blood cells adhering to the tube wall, on the serum side of the barrier. Furthermore, gel tubes, under this condition, tend to form weak or incomplete barriers. To minimize free flow, extra precaution must be taken to maintain the gel tubes in an upright position, for up to one day, upon completion of the dispensing procedure. This allows the networking to reform and retain its solid properties, broken down during the dispensing process. This again has shown to be a cumbersome procedure.
• Free flow can be inhibited by adjusting the gel formulation to achieve high "yield stresses", which is the minimum force per square unit area, required to make the gel flow. Higher yield stress promoted lower free flow properties. However, excessively high yield stress can be detrimental to the gel's ability to move, when centrifuged. In effect, provisions for reduced free flow formulations go contrary to the gel's functional ability to move during centrifugation.
• the objects of the present invention are to eliminate the above-mentioned disadvantages of the prior art and to provide a blood separation sealant having an ideal separation ability and higher reliability and capable of decreasing the overall material volume and of significantly reducing the processing cost.
• a serum separating sealant having a specific gravity at 20° C. of 1.035 to 1.065, a viscosity of 100 to 400 Pa.S and a yield stress of 100 to 400 dyne/cm 2 and comprising.
• the serum separation sealant according to the present invention comprises as the essential constituents, the components (A), (B) and (C) as mentioned above.
• the polymers usable as the component (A) in the present invention are those obtained by polymerizing the alkyl acrylate and/or alkyl methacrylate (hereinbelow referred to simply as "acryl polymer") and having a specific gravity at 20° C. of 0.94-1.06, preferably 1.030-1.045 and a viscosity of 10-140 Pa.S, preferably 50-100 Pa.S.
• the preferable number average molecular weight of the above-mentioned acryl polymer is 4000-12000.
• the polymerizable monomers usable for the preparation of the polymer (1) of the component (A) constituting the serum separation sealant according to the present invention are so-called alkyl acrylates or alkyl methacrylates.
• alkyl acrylates or alkyl methacrylates examples of such monomers are methyl(meth)acrylate (i.e., this means methyl acrylate or methyl methacrylate, the same as hereinbelow), ethyl (meth)acrylate, n-butyl(meth)acrylate, i-butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, lauryl(meth)acrylate, tridecyl(meth)acrylate, and stearyl (meth)acrylate.
• n-butyl(meth)acrylate or ethylhexyl(meth)acrylate or copolymers obtained from the combined use of these monomers are preferable, because these polymers have an appropriate viscosity, are easy to handle, and are capable of readily dispersing silica or the like therein when silica or the like is dispersed to control the specific gravity, the viscosity and the like.
• any copolymerizable monomer i.e., "additional monomer” hereinafter
• Typical examples of such copolymerizable monomers are ethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol dimethacrylate, 1,2,3-propanetriol di(meth)acrylate, divinylbenzene and the like when the additional monomer is used, the weight ratio of the polymerizable monomer represented by the formula (I) and the additional monomers
• gelatinous floating material can be controlled by making the specific gravity of the polymer higher than the specific gravity (i.e., 1.025-1.032) of the serum.
• specific gravity i.e., 1.025-1.032
• the polymer having a lower specific gravity it is effective that the polymer can be uniformly mixed with the addition of a dispersing agent in a liquid polymerization reaction mixture, whereby the dispersion of the mixture having a specific gravity higher than that of the serum can be kept at the most optimum condition.
• high viscosity was effective at maintaining the solid additives in suspension and preventing dissolution of the mixture. This is especially important for gels using low specific gravity polymers.
• the silica and/or bentonite to be used as the component (B) of the serum separation sealant according to the present invention are those as used for gel-network forming and/or as a specific gravity control agent.
• fumed silica such as "Aerosil" (Trade mark) available from Degussa can be preferably used.
• particle size of the silica the preferable particle size is 50 m ⁇ or less, more preferably 5 to 40 m ⁇ .
• any bentonite can also be used in the present invention.
• "BENTONE" Trade mark (smectite/hectorite) available from NL Chemicals can be preferably used.
• the silica and/or bentonite are used in an amount of 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, based upon 100 parts by weight of the acrylic polymer (A).
• the amount of the component (B) is less than 1 part by weight, the desired structural viscous properties cannot be obtained, and therefore, the free movability becomes high. Contrary to this, when the amount of the component (B) is more than 10 parts by weight, the specific gravity becomes high and the movability of the barrier formation is decreased.
• At least one surfactant selected from the group consisting of fluorocarbon based surfactants, polyester modified alkylpolysiloxane based surfactants, and polyether modified alkylpolysiloxane based surfactants is formulated in an amount of 0.01 to 2 parts by weight, preferably 0.05 to 1.8 parts by weight, based upon 100 parts by weight of the above-mentioned acryl polymer (A).
• the formulation amount is less than 0.01 part by weight, it is difficult to obtain the necessary viscosity, and therefore, the free movability becomes high. Contrary to this, when the formulation amount is more than 2 parts by weight, the viscosity is increased and the movability of the barrier formation is decreased.
• the fluorocarbon-based surfactants (C-1) usable as the component (C) of the present invention may include, for example, those having the formula (II): ##STR3## wherein n is an integer of 1-20, m is an integer of 10-20 and R denotes an alkyl group, preferably having 1 to 20 carbon atoms.
• surfactants examples include MEGAFAC. F142/F144 (Trade mark) by Dainippon Ink and Chemicals, Inc. and FLUORAD FC170C. (Trade mark) by Sumitomo 3M Co., Ltd.
• the polyether modified alkylpolysiloxane based surfactants (C-3) usable as the component (C) of the present invention may include, for example, those having the formula (III): ##STR4## wherein R 1 denotes an alkyl group, preferably having 1 to 20 carbon atoms, POA denotes a polyoxyalkyl (R--O--R 1 ) group, x is an integer of 8-120, y is an integer of 8-120, and R is an alkyl group, preferably having 1 to 20 carbon atoms.
• Examples of such polyether modified alkylpolysiloxane based surfactants (C-3) are "Toray-Dow Corning SH190, 192, SF 3748, SH 3746, SH 3749, SH 3771, SH 8400, SH 8700 (Trade mark) available from Toray-Dow Corning K.K.
• the polyester modified alkylpolysiloxane based sulfonates (C-2) usable as the component (C) of the present invention may include, for example, those having the formula (IV): ##STR5## wherein R denotes hydrogen or an alkyl group, preferably having 1 to 20 carbon atoms, R 2 and R 3 denote independently an alkyl group, preferably having 1 to 20 carbon atoms, and x and y are independently 8 to 120.
• polyester modified alkylpolysiloxane based surfactants are BYK310 or 370 (Trade mark) available from BYK Chemic K.K.
• the serum separation sealant according to the present invention may optionally include, in addition to the essential constituents (A), (B) and (C), 0.01 to 1 part by weight, preferably 0.05 to 0.8 parts by weight, based on 100 parts by weight of the component (A), of titanium dioxide and/or calcium carbonate as the optional component (D) and 0.02 to 1 part by weight, preferably 0.1 to 0.8 parts by weight, based on 100 parts by weight of the component (A), of a titanium based coupling agent (E).
• the amount of the component (D) is out of the above-mentioned range, it becomes difficult to obtain the desired specific gravity.
• the amount of the titanium based coupling agent of the component (E) is less than 0.02 parts by weight, the viscosity is increased and the desired movability of barrier formation is difficult to obtain.
• the titanium based coupling agents of the component (E) are the following various Prenact materials (Trade mark) available from Ajinomoto Co., Ltd.
• KRTTS isopropyl-triisostearyltitanate
• KR-9S isopropyltridodecylbenzene sulfonyl titanate
• KR-12 isopropyltri(dioxylphosphate)titanate ##STR8##
• titanium based coupling agent improve the affinity of the polymer with the filler and the dispersibility by chemically associating with the acrylic polymer and the inorganic portion, whereby the dissolution of the mixture is prevented.
• the serum separation sealant has a specific gravity at 20° C. of 1.035 to 1.065, preferably 1.04 to 1.055, a viscosity of 100 to 400 Pa.S, preferably 140 to 320 Pa.S and a yield stress of 100 to 400 dyne/cm 2 preferably 150 to 300 dyne/cm 2 .
• these sealants exhibited a Newtonian viscosity phenomenon and exhibited an excessive free flow ability, and therefore, were not practically usable at all.
• the yield stress of this sealant was zero.
• a copolymer of 15 parts of lauryl methacrylate, 24 parts of n-butyl acrylate, 60 parts of ethyl hexyl methacrylate and 1 part of ethylene glycol dimethacrylate and having a specific gravity of 0.950 and a viscosity of 20 Pa.S was used as a sealant.
• Added to 100 parts of this polymer was fine silica powder in an amount of up to 20 parts by weight and a sealant having a specific gravity of 1.05 and a viscosity of 250 Pa.S was produced.
• Various blood separation sealants according to the present invention were produced. The particulars of these sealants are shown in Tables 2 and 3.
• As the component (A), various polymers polymerized from n-butyl acrylate (NBA), ethylhexyl acrylate (EHA) and ethylene glycol dimethacrylate (EGDM) were used in the compositions shown in Tables 2 and 3.
• the viscosities and the specific gravities were as shown in Tables 2 and 3.
• silica such as Aerosil (Trademark) R805, R812, R972, A130 and OX50 and bentone (i.e., B-38 available from NL Chemicals Co.) were used in an amount shown in Tables 2 and 3.
• SH190 i.e., polyether modified alkyl polysiloxane based surfactant available from Toray-Dow Corning Silicone K.K.
• BYK370 i.e., polyester modified alkyl polysiloxane-based surfactant
• F144, F-177 i.e., fluorocarbon based surfactant
• FC170C i.e., fluorocarbon based surfactant available from Sumitomo 3M Co., Ltd.
• optional component (D) calcium carbonate (CaCO 3 ) and titanium dioxide (TiO 2 ) were used and as the optional component (E), and a thitanin based coupling agent, KRTTS, KR-9S and KR-12 (i.e., PRENACT of Ajinomoto Co., Ltd.) was used in an amount shown in Tables 2 and 3.
• silica and/or bentone are a network former and the alkylpolysiloxane and/or fluorocarbon based surfactants were included to enhance the viscosity of the sealant.
• the roll milling can be reduced to two passes or less, or eliminated altogether.
• a titanium coupling agent can also be incorporated in the formulation to promote improved dispersion of the network former/filler contents.
• the production of the acrylic polymer generally involves the dropwise addition of the monomer components, to 30-60 parts by weight of an appropriate solvent (e.g., xylene, toluene). After the completion of monomer addition, the mixture is aged to allow for the complete reaction and is then evaporated to remove the solvent.
• an appropriate solvent e.g., xylene, toluene
• Tables 2 and 3 The formulation and various physical properties and the like are shown in Tables 2 and 3.
• the units of the viscosity and the yield stress in the Tables are Pa.S and dyne/cm 2 , respectively.
• the silicone fluid as a polymer was a dimethylpolysiloxane, made available by Dow Corning Corp. and identified as a 200 Series Silicone Fluid. It had a viscosity of about 12,500 centistokes at 25° C. and a specific gravity of 0.975.
• the silica particles consisted of very finely divided particles having a surface area of about 110 m 2/ g and a specific gravity of about 2.2.
• the silica particles were obtained from Degussa, Inc., and identified by the designation D.17.
• the silicone fluid and silica particles were initially mixed together in the indicated amounts by pre-mixing to obtain a gel-like composition having an initial viscosity of about 200,000.
• the component (C), SH 190 i.e., polyether modified alkyl polysiloxane based surfactant available from Toray-Dow Corning Silicone K.K.
• SH 190 i.e., polyether modified alkyl polysiloxane based surfactant available from Toray-Dow Corning Silicone K.K.
• Viscosities of all samples were measured using an EHD type cone and plate viscometer at variable shear rates. Viscosities with their corresponding shear rates can be used to estimate yield stress according to Casson plot theory.
• Dispensed gel tubes are maintained in an upright position for a time period of 3 minutes.
• tube materials containing 1.8 ml of gel were stored at 60° C. for 1 month, as a way of simulating normal shelf aging of over 1 year. Approximately 8 ml of blood were collected in each tube and allowed to clot for up to 1 hr. The samples were then centrifuged at 800 G for 10 min. Normal procedures usually involve centrifuging ⁇ 1300 G for 10 min. However, to ensure reliability, a stricter centrifuging standard of 800 G ⁇ 10 minutes was chosen.
• Example 5 which utilized only planetary mixing in its manufacture, demonstrated it is possible to simplify the production processing and still retain the same performance qualities as in the other Examples. Gels similar to Example 2 (Comparative Example), by virtue of high silica content, made it impossible to conduct any type of simplification. A high shearing action generated by the roll mill was compulsory for manufacture.
• a representative formulation in accordance with Example 3-16 was produced and further evaluated under the regimen of Therapeutic Drug Monitoring (TDM) procedures.
• TDM Therapeutic Drug Monitoring
• the test involved comparisons of drug recovery from blood samples, over a period of 1 hr. to 3 days, using the composite gel formula.
• the drugs monitored included digoxin, disopyramide, lidocaine, procainamide, quinidine, gentamicin, acetominaphen, valproic acid, phenytoin, carbamazepine, and phenobarbital. Analysis showed a very high standard of recovery, demonstrating the gel materials inertness with respect to these drugs.

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• 1993
  • 1993-11-05 JP JP27628893A patent/JP3260219B2/ja not_active Expired - Lifetime
  • 1993-11-10 EP EP9393308974A patent/EP0597690A3/en not_active Withdrawn
  • 1993-11-12 US US08/151,199 patent/US5438000A/en not_active Expired - Lifetime
  • 1993-11-12 CA CA002102993A patent/CA2102993A1/en not_active Abandoned

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